Short-term habituation of the longfin squid (Doryteuthis pealeii) to pile driving sound

Abstract

Offshore windfarms are a key renewable solution to help supply global energy needs. However, implementation has its challenges, including intense pile driving sound produced during constructions, which can affect marine life at the individual level, yet impacts at the group level remain poorly studied. Here, we exposed groups of longfin squid (Doryteuthis pealeii) in cages at multiple distances from consecutive pile driving events and sought to quantify responses at both individual and group levels. Pile driving induced short-term alarm responses at sound levels (in zero-peak) of 112–123 dB re 1 µm s−2 that were similar to those measured at kilometre scale from offshore windfarm constructions. The rate of individual alarm responses quickly decreased both within and across consecutive pile driving events, a result consistent with previous laboratory studies. Despite observing dramatic behavioural changes in response to initial pile driving sound, there were no significant differences in squid shoaling areas before and during exposure, showing no disruption of squid collective behaviours. Our results demonstrate rapid habituation of squid to pile driving sound, showing minimal effects on this ecologically and commercially key taxon. However, future work is now needed to assess responses of wild squid shoals in the vicinity of offshore windfarm constructions.